1. Field of the Invention
The present invention relates to a motor cooling structure, specifically to a cooling structure that cools a motor including a coil end cover interposed between a coil end and a motor case.
2. Description of the Related Art
Cooling structures that cool a motor are conventionally known (for example, Japanese Patent Application Publication No. 2006-197772 (JP-A-2006-197772)). In the cooling structure, a coolant is supplied by a pump through a liquid passage to the coil of the motor. According to this cooling structure, the circulation of the coolant absorbs the heat generated by the motor, thereby cooling the motor.
In the cooling structure described in JP-A-2006-197772, the cooling efficiency of the motor may be improved by increasing the contact area between the coil end of the motor and a coolant. In a structure that cools the motor only by circulating the coolant in the liquid passage, the heat generated by the motor is absorbed by the coolant, and released to the outside. However, there is no other route for the heat to be released. Specifically, because air at the periphery of the coil end also acts as a heat insulator, a route that transfers the heat from the coil end to the motor case may be insufficient to adequately cool the motor.